关键词: 涡轮, 涡轮试验, 效率, 封严气, 雷诺数, 叶尖间隙

Abstract:

Turbine rig test is a most important way to evaluate the turbine component performance. In the test， the accuracy of efficiency measurement is very important to the test results， but will be affected by many process factors. Based on the results of low-pressure turbine rig test， this paper analyzes the effects of inlet and outlet flow field， sealing flow temperature/mass flow rate， Reynolds number， tip clearance， mechanical loss and efficiency definition on turbine test efficiency， so as to provide reference for turbine performance test scheme design， instrumentation design and test data analysis. The uniformity of inlet total temperature can be improved by setting the sealing flow to have the same temperature as the main flow and covering the inlet outer casing with thermal insulation material during test. The circumferential distribution of the turbine exit measurement points is strongly correlated with the phase of the last guide vane. The circumferential arrangement of the exit probe should consider the influences of the wake and main flow regions of the last guide vane； otherwise， an efficiency deviation exceeding 0.1% may occur. The influences of the sealing flow temperature ratio and flow ratio on the turbine efficiency must be considered and strictly controlled in the turbine test. For a low-pressure turbine， the efficiency decreases by 0.11% with 0.1 increase in the seal air temperature ratio， and by 0.29% with 1% increase in the mass flow rate. The Reynolds number has a significant impact on the efficiency of the low-pressure tur-bine. When collecting turbine map data by using the scheme with a fixed exit total pressure， the difference in low-pressure turbine efficiency caused by change of Reynolds number can reach 1%. Turbine map tests should be conducted at the Reynolds number that is above the self-simulation region or is equal for different test conditions， or the effect of Reynolds number could be corrected after the test. In addition， this paper also shows the effect of blade tip clearance， mechanical losses， and efficiency definition on test efficiency.

Key words: turbine, rig test, efficiency, sealing flow, Reynolds number, tip clearance